Arrangement for quartz oscillators



Feb. 13, 1934.

I w. KUMMERER 1,946,698

ARRANGEMENT FOR QUARTZ OSCILLATORS Filed April 14, 1932 INVENTOR WILHELM KUMMERER vwm ATTORNEY Patented Feb. 13, 1934 UNITED STATES ARRANGEMENT FOR QUARTZ OSCILLATORS Wilhelm Kummerer, Berlin, Germany, assignor to Telefunken Gesellschaft fur Drahtlose Telegraphic in. b. H., Berlin, Germany, a corporation of Germany Application April 14, 1932, Serial No. 605,142, and in German April 14, 1931 7 Claims.

It has been found that the frequency of crystalecontrolled generators is considerably dependent upon the temperature of the quartz crystal. This temperature is a function of the electrical load and as a result it fluctuates as the load varies. By confining the crystal inside a thermostatically regulated chamber, temperature fluctuations of the said sort may be obviated so much better, the better the thermal contact between the quartz and the thermostat. On the other hand, however, it is necessary that a certain airgap or distance should be preserved between the quartz and one of the electrodes of the quartz, the size of said gap being approximately of 1 mm.

The present invention has the purpose to preserve good heat transfer conditions between the quartz and the electrodes in spite of the presence of the said air-gap. The same consists in an artificial enlargement of the radiation of the quartz which consists in that the quartz and/or the electrodes of the quartz are covered with a substance whose absorptivity for thermal radiation is high. It will be understood that also the electrodes of the quartz may consist of some such material.

The adoption of the invention is particularly important in quartz oscillators which are confined inside a vacuous space since in that case heat conduction across the air-gap is entirely absent.

One special embodiment of the basic idea of the invention is shown in the figure. Referring to the same, 1 and 2 denote the electrodes of the quartz, 3 is the quartz crystal being superficially coated with the heat-radiator substance 4. The top electrode of the quartz crystal, upon the face turned toward the quartz, is covered with a heatabsorbing layer 5, while upon the side turned away from the quartz it has a coating 6 which, in turn, improves the heat radiation on the body '7. The absorption of radiations issuing from the coat 6 will be still further improved if the body 7 upon its inner face is covered with a heat-absorbing layer 8. The temperature of the body '7 is kept constant by a suitable device. The interior of the body is evacuated.

The preferably method is to coat the crystal with a thin film of soot, though also any other color or dye of a matt black applicable in as thin a coat as feasible may be used. The material to be considered for blackening the crystal need not possess any particular thermal properties (thermal co-efficient).

I claim:

1. In combination, an air tight container coated on its inner surface with a heat absorbing substance, a piezo-electric crystal within said container and in direct contact therewith, an electrode spaced a slight distance away from said (Cl. I'll-32 crystal, said electrode being coated on its upper and lower surfaces with a heat absorbing sub stance.

2. Piezo-electric crystal apparatus comprising a crystal and a plurality of electrodes, said crystal being interposed between said electrodes so as to provide an air gap between the top surface of said crystal and one of the electrodes, and at least one of said electrodes being coated with material having a high thermal radiation coefficient.

3. Piezo-electric crystal apparatus comprising a crystal, electrodes therefor and a holder, said crystal interposed between and spaced apart from said electrode so as to provide an air gap, said electrodes and holder being coated with material possessing high thermal radiation coeflicient characteristics.

4. A holder for piezo-electric crystals comprising an evacuated chamber, a plurality of electrodes within said chamber, a crystal interposed between said electrodes, a spacing member to space said electrodes so as to provide an air gap between said electrodes, and a coating on the face of said crystal and one of said electrodes of material possessing a high thermal radiation coefficient.

5. A holder for piezo-electric crystals comprising an evacuated chamber, a plurality of electrodes within said chamber, a crystal interposed between said electrodes, a spacing member to space said electrodes so as to provide an air gap between said electrodes, and a coating of soot on the face of said crystal and one of said electrodes so as to present a high thermal radiation coefficient.

6. A holder for piezo-electric crystals comprising an evacuated chamber having its inner surface coated with a heat absorption layer, a plurality of electrodes within said chamber, a crystal interposed between said electrodes, a spacing member to space said electrodes so as to provide an air gap between said electrodes, and a coating on the face of said crystal and one of said electrodes of material possessing a high thermal radiation coefiicient.

'7. A holder for piezo-electric crystals comprising an evacuated chamber having its inner surface coated with a black matt coating to provide a heat absorption layer, a plurality of electrodes within said chamber, a crystal interposed between said electrodes, a spacing member to space said electrodes so as to provide an air gap between said electrodes, and a coating on the face of said crystal and one of said electrodes of material possessing a high thermal radiation coefficient.

WILHELM KUMMERER. 

